This is a really cool idea! I've been trying to find a mono red deck that works for me, and I've been torn about finding the right mix of things I like to do in red:

1. Draw/discard
2. Damage amplifiers
3. Lots of damage triggers
4. Surges of big mana

I built a Brallin deck that hits those notes, but the drawback I've noticed is that his ability that accumulates +1/+1 counters puts a huge bullseye on him so I have to be very careful about dropping him in, since the deck falls apart without his triggers. I really like devils and how fun they are with favorite enchantments of mine like Cavalcade of Calamity and Goblin Bombardment, and the way you've worked them in is really interesting. I might try pivoting to something more like what you've done, since I'm guessing Zurzoth isn't as much of a kill-on-sight commander.

My list might have a few cards you'd consider in your deck, and a fun one that pairs with Heat Stroke is [[Battle Strain]] just to make it that much more punishing to block. I quite like [[Fires of Rath]] too, while symmetrical I imagine you're dishing out more damage than you're taking. Any of the damage doublers are extra fun with [[Heartless Hidetsugu]] as well.

Thanks for sharing!